"I've seen an uptick in flu cases over this past week," Wichita Falls ER Now Dr. Courtney Walker said. "I think as we progress throughout January which is our peak season we'll see more and more."

The cold weather helps spread it.

"Dry air kind of dries out your mucous membrane and lessens your immune system as far as that is concerned," Dr. Walker said.

Dr. Walker said a lowered immune system caused by the flu puts many at risk who are already vulnerable, the elderly, children and anyone with a pre-existing condition.

The flu already took the lives of dozens across the country. Nine people have died this flu season in Dallas County. At least three of them had pre-existing conditions.

"The fact that their immune system is not mounting an appropriate response is not fighting the virus like a healthy person's immune system would fight the virus," Dr. Walker said.

She said the best method is to act.

"If you are around an elderly person, the best thing you can do is get a flu shot and protect yourself from getting the flu and passing it on," Dr. Walker said.

Dr. Walker said typically if you get the flu then your body should develop antibodies to fight against it and prevent you from getting it again but that is not the case 'especially if your immune system is weakened so you can definitely get it more than once.'

If you have a fever, start to feel sluggish, confused and have difficulty breathing, Dr. Walker said 'see a doctor immediately.'

She also said flu season can last until April so it is not too late for you to get a flu shot.

Wichita Falls - Wichita County Public Health District gives flu shots if you still need to get one. Call its immunization clinic 940-761-6841 to schedule an appointment.

(AP Photo/Marcio Jose Sanchez). University of California students, from left, Anjali Banerjee, Alice Ma and Tyler Heintz walk near the university's campus Wednesday, June 6, 2018, in, Berkeley, Calif. The students who were in Nice, France when a terror...

University of California, Berkeley students who were in the French city of Nice when a man drove a 19-ton truck through the crowd, killing their classmate and 85 other people, have turned their grief into building...

University of California, Berkeley students who were in the French city of Nice when a man drove a 19-ton truck through the crowd, killing their classmate and 85 other people, have turned their grief into building a tech startup to fight terrorism.